This project is a coordinated chemical and immunological study of the roles played by the cell-surface polysaccharides and peptido-polysaccharides of some pathogenic yeasts and fungi in the various biological functions of these organisms. Included is a study of their roles in morphology, immunogenicity and pathogenicity. Previous studies have concentrated on a peptido-galactomannan from Cladosporium werneckii and a peptido-rhamnomannan from Sporothrix schenckii. Both of these have been purified and characterized and have been shown to be involved in reactivity with antibody and in delayed hypersensitivity (DH). A major goal of the project is the dissociation of the complex antigens into their polysaccharide and peptide components. Two methods, one using chemical and the other enzymatic procedures, are planned. When the two components are available it will be possible to test their immunological specificity separately and to determine the role played by the polysaccharide and peptide moieties in both facets of the immune response. Preliminary evidence indicates that the former is involved in reactivity with antibody and in immediate allergy whereas the latter is responsible for DH and will be more important in immunity to fungal infection. In a related study, the role of rhamnomannans in the morphology of S. schenckii, particularly in the change from yeast to mycelial forms (the former is the pathogenic form), will be investigated. These data are pertinent to elucidating the relationship of S. schenckii to various morphologically related anasciqerous species of Ceratocystis found in nature. The ability of certain fungi to become pathogenic in man is a poorly understood but important problem in medical mycology.